Multi-Vendor Marketplace creation

I am looking for a skilled full-stack developer and designer who is experienced in building marketplaces.

I am not a developer myself, thus I don't know what's the best and most efficient way to create such a website.
I read about Wordpress, which seems not to be suitable for a high number of user.
Maybe Magento 2 would be an option, but it seems like a website developed from scratch is always the best option, right?

Furthermore I have a few specific questions:

1. One of my marketplace ideas would focus on digital products. Is it possible with the platform to give the sellers the option to send videos and images easily? Or can you integrate and easy-to-use API for that purpose?

2. The payment process works best with PayPal and Stripe, right? But how can the billing/invoicing VAT taxation and accounting process can be automated? Because there are pretty tough laws on those issues here in Germany.

3. What would be the best hosting option? I heard good things about AWS and Digital Ocean.

In conclusion: A bit of advise from an expert would be appreciated and an estimate on how much the development would cost as well.


Regards,

Malte